1. Field of the Invention
The present invention relates to methods of producing carboxylic acid ester derivatives of formulae (I) and (II), which are useful, for instance, as intermediates for producing an anti-hypercholesterolemic agent having an inhibitory effect on 3-hydroxy-3-methylgulary-CoA Reductase (hereinafter referred to as HMG-CoA Reductase), in particular, through deprotection or the like. The present invention also relates to intermediates for use in the methods of producing the carboxylic acid ester derivatives: ##STR3## wherein R.sup.1 and R.sup.2 are independently a protective group for hydroxyl group, or R.sup.1 and R.sup.2 integrally constitute a protective group for hydroxyl groups; R.sup.3 is an alkyl group having 1 to 12 carbon atoms, or an aryl group; and R.sup.4 is a substituted aryl group, a substituted heterocyclic group, a substituted vinyl group, or a substituted cycloalkenyl group. ##STR4## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are respectively the same as defined in the above formula (I).